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<h1>Data Access Overview</h1>
<p>Data Access is the original OPC specification, adapted into the core 
 of OPC UA and defined in <a href="http://www.opcfoundation.org/ua/part8"><?rh-udv_start 
	 name="UaSpec08" ?>UA Specifications Part 8 - Data Access (http://www.opcfoundation.org/ua/part8)<?rh-udv_end ?></a>.</p>
<p>Intended for continuous data acquisition from a PLC/controller, and 
 providing the following capabilities:</p>
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		<td><p style="text-align: center;"><span style="font-weight: bold;">Capability</span></p></td>
		<td><p><span style="font-weight: bold;">Description</span></p></td>
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		<td><p style="text-align: center; font-weight: bold;">Discovery</p></td>
		<td><p>The ability to locate other OPC UA products available on 
		 a PC/network.</p></td>
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		<td><p style="text-align: center; font-weight: bold;">Browsing</p></td>
		<td><p>The ability to browse the address space of a Server to obtain 
		 a list of usable Nodes.</p></td>
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		<td><p style="text-align: center; font-weight: bold;">Read</p></td>
		<td><p>To read 1...n Nodes in a single call and obtain the value, 
		 quality, timestamp, and a success/failure code for each element 
		 - all within a single call.</p></td>
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		<td><p style="text-align: center; font-weight: bold;">Write</p></td>
		<td><p>To write to 1...n Nodes in a single call while obtaining 
		 the success/failure code for each individual element.</p></td>
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		<td><p style="text-align: center; font-weight: bold;">Subscription</p></td>
		<td><p>The ability to request a Server to monitor Nodes and to 
		 send a notification to the Client when the value changes.</p></td>
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<p>There are many other features of OPC UA that are inherited by the Data 
 Access <span style="font-style: italic;">profile</span>.</p>
<p>There are 2 demonstration applications available:</p>
<ul type="disc">
	<li><p><a href="DAServerOverview.htm">Data Access Server - Overview</a></p></li>
	<li><p><a href="DAClientOverview.htm">Data Access Client - Overview</a></p></li>
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